The increase in data rates of data carried by optical communication networks that is experienced today makes switching operations that require optical-to-electronic and electronic-to-optical conversions of communicated information undesirable. On the other hand, all-optical switching in all-optical communication networks, particularly in applications that involve wavelength division multiplexing (WDM) and in applications that require speedup and slow-down of the communicated information, is not trivial. Thus, efficient techniques for all-optical switching that supports speedup and slow-down of communicated information in non-WDM based optical communication networks and in WDM based optical communication networks are still required.
A technique that uses a delay line together with multiplexing and modulation in order to increase a data rate of data carried over a single fiber optic cable is described in an article entitled “Mining the Optical Bandwidth for a Terabit per Second”, by Alan Eli Willner in IEEE Spectrum, April 1997, pp. 32–41. However, the technique described by Willner is not suitable for use with a plurality of separate fiber optic cables carrying data after the data is already modulated, and is also not suitable for use in cases where there is no synchronization among separate fiber optic cables carrying data.
Some aspects of technologies and art related to all-optical clock-recovery in optical communication networks are described in the following publications:
an article entitled “Polarization Insensitive Widely Tunable All-Optical Clock Recovery Based on AM Mode-Locking of a Fiber Ring Laser”, by Wang et al in IEEE Photonics Technology Letters, Vol. 12, No. 2, February 2000, pp. 211–213;
an article entitled “Ultra-High-Speed PLL-Type Clock Recovery Circuit Based on All-Optical Gain Modulation in Traveling-Wave Laser Diode Amplifier”, by Kawanishi et al in Journal of Lightwave Technology, Vol. 11, No. 12, December 1993, pp. 2123–2129; and
an article entitled “Prescaled 6.3 GHz clock recovery from 50 GBit/s TDM optical signal with 50 GHz PLL using four-wave mixing in a traveling-wave laser diode optical amplifier”, by Kamatani et al in Electronics Letters, Vol. 30, No. 10, May 12, 1994, pp. 807–809.
Some aspects of technologies and art related to delay line techniques are described in the following publications:
an article entitled “Variable optical delay line with diffraction-limited autoalignment” by Klovekorn et al in Applied Optics, Vol. 37, No. 10, Apr. 1, 1998, pp. 1903–1904;
an article entitled “Picosecond-Accuracy All-Optical Bit Phase Sensing Using a Nonlinear Optical Loop Mirror”, by Hall et al in IEEE Photonics Technology Letters, Vol. 7, No. 8, August 1995, pp. 935–937; and
an article entitled “An Ultrafast Variable Optical Delay Technique”, by Hall et al in IEEE Photonics Technology Letters, Vol. 12, No. 2, February 2000, pp. 208–210.
Some aspects of technologies and art related to all-optical demultiplexing techniques are described in the following publications:
an article entitled “Compact 40 Gbit/s optical demultiplexer using a GaInAsP optical amplifier”, by Ellis et al in Electronics Letters, Vol. 29, No. 24, Nov. 25, 1993, pp. 2115–2116;
an article entitled “Bit-Rate Flexible All-Optical Demultiplexing Using a Nonlinear Optical Loop Mirror”, by Patrick et al in Electronics Letters, Vol. 29, No. 8, Apr. 15, 1993, pp. 702–703; and
an article entitled “All-Optical High Speed Demultiplexing with a Semiconductor Laser Amplifier in a loop Mirror Configuration”, by Eiselt et al in Electronics Letters, Vol. 29, No. 13, Jun. 24, 1993, pp. 1167–1168.
Some aspects of technologies and art related to WDM based and non-WDM based optical communication networks and to optical switching techniques and elements associated therewith are described in the following publications:
The Communications Handbook, CRC Press & IEEE Press, 1997, Editor-in-Chief Jerry D. Gibson, Chapter 65, pp. 883–890;
an article entitled “Optical switching promises cure for telecommunications logjam”, by Jeff Hecht in Laser Focus World September 1998, pp. 69–72;
a technology brief entitled “Lucent Upgrades Wavestar to 320-Channel, 800-Gb/s Transmission”, in Photonics Spectra, June 2000, pp. 46;
an article entitled “Design and Cost Performance of the Multistage WDM-PON Access Networks”, by Maier et al in Journal of Lightwave Technology, Vol. 18, No. 2, February 2000, pp. 125–143;
an article entitled “All-optical networks need optical switches”, by Jeff Hecht in Laser Focus World, May 2000, pp. 189–196;
an article entitled “Record Data Transmission Rate Reported at ECOC 96”, by Paul Mortensen in Laser Focus World, November 1996, pp. 40–42;
an article entitled “Multiple Wavelengths Exploit Fiber Capacity”, by Eric J. Lerner in Laser Focus World, July 1997, pp. 119–125;
an article entitled “Advances in Dense WDM Push Diode-Laser Design”, by Diana Zankowsky in Laser Focus World, August 1997, pp. 167–172;
an article entitled “Multistage Amplifier Provides Gain Across 80 nm”, by Kristin Lewotesky in Laser Focus World, September 1997, pp. 22–24;
an article entitled “WDM Local Area Networks”, by Kazovsky et al in IEEE LTS, May 1992, pp. 8–15;
an article entitled “Optical Switches Ease Bandwidth Crunch”, by Rien Flipse in EuroPhotonics, August/September 1998, pp. 44–45;
an article entitled “Speed Demons: Is “Faster Better and Cheaper?”, by Stephanie A. Weiss in Photonics Spectra, February 1999, pp. 96–102;
an article entitled “Wavelength Lockers Keeps Lasers in Line”, by Ed Miskovic in Photonics Spectra, February 1999, pp. 104–110;
an article entitled “Optical switches pursue crossconnect markets”, by Hassaun Jones-Bay in Laser Focus World, May 1998, pp. 153–162;
a conference review entitled “Optical amplifiers revolutionize communications”, by Gary T. Forrest in Laser Focus World September 1998, pp. 28–32;
an article entitled “Combining gratings and filters reduces WDM channel spacing”, by Pan et al in Optoelectronics World, September 1998, pp. S11–S17;
an article entitled “Demand triggers advances in dense WDM components”, by Raymond Nering in Optoelectronics World, September 1998, pp. S5–S8;
an article entitled “Optical Networks Seek Reconfigurable Add/Drop Options”, by Hector E. Escobar in Photonics Spectra, December 1998, pp. 163–167;
an article entitled “Ultrafast Optical Switch Unveiled”, by Michael D. Wheeler in Photonics Spectra, December 1998, pp. 42;
an article entitled “Data express Gigabit junction with the next-generation Internet”, by Collins et al in IEEE Spectrum, February 1999, pp. 18–25;
an article entitled “Designing Broadband Fiber Optic Communication Systems”, by Juan F. Lam in Communication Systems Design magazine, February 1999, pp. 1–4 at http://www.csdmag.com;
an article entitled “Terabit/second-transmission demonstrations make a splash at OFC '96”, in Laser Focus World, April 1996, pp. 13;
an article entitled “Multigigabit Networks: The Challenge”, by Rolland et al in IEEE LTS, May 1992, pp. 16–26;
an article entitled “Direct Detection Lightwave Systems: Why Pay More?”, by Green et al in IEEE LCS, November 1990, pp. 36–49;
an article entitled “Photonics in Switching”, by H. Scott Hinton in IEEE LTS, August 1992, pp. 26–35;
an article entitled “Advanced Technology for Fiber Optic Subscriber Systems”, by Toba et al in IEEE LTS, November 1992, pp. 12–18;
an article entitled “Fiber amplifiers expand network capacities”, by Eric J. Lerner in Laser Focus World, August 1997, pp. 85–96;
an article entitled “Technologies for Local-Access Fibering”, by Yukou Mochida in IEEE Communications Magazine, February 1994, pp. 64–73;
an article entitled “Wavelength Assignment in Multihop Lightwave Networks”, by Ganz et al in IEEE Transactions on Communications, Vol. 42, No. 7, July 1994, pp. 2460–2469;
an article entitled “Wavelength-Division Switching Technology in Photonic Switching Systems”, by Suzuki et al in IEEE International Conference on Communications, ICC '90, pp. 1125–1129;
an article entitled “Branch-Exchange Sequences for Reconfiguration of Lightwave Networks”, by Labourdette et al in IEEE Transactions on Communications, Vol. 42, No. 10, October 1994, pp. 2822–2832; and
an article entitled “Use of Delegated Tuning and Forwarding in Wavelength Division Multiple Access Networks”, by Auerbach et al in IEEE Transactions on Communications, Vol. 43, No. 1, January 1995, pp. 52–63.
Additionally, asynchronous time-division switching is described in The Communications Handbook, CRC Press & IEEE Press, 1997, Editor-in-Chief Jerry D. Gibson, Chapter 51, pp. 686–700. Multiple access methods for communications networks are described in The Communications Handbook, CRC Press & IEEE Press, 1997, Editor-in-Chief Jerry D. Gibson, Chapter 46, pp. 622–649.
U.S. Pat. No. 5,170,273 to Nishio describes a cross-talk reducing optical switching system which receives electrical digital signals at its input terminal.
U.S. Pat. No. 5,191,457 to Yamazaki describes a WDM optical communication network in which optical beams are modulated by channel discrimination signals of different frequencies.
U.S. Pat. No. 5,194,977 to Nishio describes a wavelength division switching system with reduced optical components using optical switches.
U.S. Pat. No. 5,557,439 to Alexander et al. describes wavelength division multiplexed optical communication systems configured for expansion with additional optical signal channels.
U.S. Pat. No. 5,680,490 to Cohen et al. describes a comb splitting system which demultiplexes and/or multiplexes a plurality of optical signal channels at various wavelengths.
U.S. Pat. No. 5,712,932 to Alexander et al. describes reconfigurable wavelength division multiplexed systems which include configurable optical routing systems.
U.S. Pat. Nos. 5,724,167 and 5,739,935 to Sabella describe an optical cross-connect node architecture that interfaces plural optical fiber input and output links, each link containing plural wavelength channels.
U.S. Pat. No. 5,457,687 to Newman describes reactive congestion control in an ATM network where the network is formed by the interconnection of nodes each including a forward path for transfer of information from source to destination through the network and a return path for returning congestion control signals.
Copending U.S. patent application Ser. No. 09/126,378 filed on Jul. 30, 1998 and assigned to Doron Handelman, now U.S. Pat. No. 6,404,522, describes improvements in communication performance of an optical communication system that communicates data via N different channel wavelengths using WDM.
Copending U.S. patent application Ser. No. 09/389,345 filed on Sep. 3, 1999 and assigned to Doron Handelman, now U.S. Pat. No. 6,574,018, describes a network control system that may be embodied in various elements of a communication network that communicates optical signals multiplexed by WDM. The network control system may limit a number of channel wavelengths actually used for communicating optical signals to an end node, and control and modify data rates carried over channel wavelengths multiplexed by WDM.
The disclosures of all references mentioned above and throughout the present specification are hereby incorporated herein by reference.